VXML... how to integrate

I am working on migrating my phone system from trixbox to 3CX.
I have a number of custom dial plans and PHP-based AGI scripts that access various databases to track trouble tickets.
In selecting 3CX I see that it is possible to use VXML to accomplish the task of IVR-based data access. I am however clueless as how to deploy a VXML script in 3CX without the VAD.
How do you make a VXML script work in 3CX without the VAD?
Where do I put the script in the filesystem?
Where in the 3CX GUI do I point it at the script?